The present invention relates to the measurement of electrical signals and, in particular, to the measurement of current in response to an applied voltage.
It is common to apply a known voltage to a device under test (DUT) and to measure the resulting current. In particular, the potential at the DUT may be fed back to a voltage source control to ensure that the desired voltage is applied to the DUT. A sense resistor in series with the DUT is used to sense a voltage that is proportional to the current through the DUT. The feedback loop bandwidth is chosen to provide a stable loop with an acceptable time for transients to settle.
In many cases of interest, the DUT has a substantial capacitive component (e.g., greater than 10 uF). When such a high capacitance DUT is encountered by a measurement system configured for low capacitance DUTs, the capacitance of such a high capacitance DUT will often result in the overall measurement system becoming unstable.